- The distinct expression patterns of many members of the phylogenetically conserved homeobox ("HOX") gene family in both developing and adult skin implicate this group of controller genes in patterning and regenerative processes of the skin. The principal investigator has preliminary data that transgenic mice over-expressing Hoxc13 (GC13 mice) in pre- and postnatal skin exhibit hyperproliferation of follicular and epidermal keratinocytes. These mice exhibit alopecia and a progressive skin defect resembling ichthyosis. This animal model will be used to define the molecular mechanisms underlying these abnormalities, by studying expression of Hoxc13 and its neighbor Hoxc13, screening for differentially expressed mRNAs in skin of normal versus Hoxc13-mutant mouse skin, comparison of Hox12 knockout versus dominant gain-of-function mice, and transcriptional regulation of Hoxc13 and Hoxc12.